Baffle construction for flare seal drums

ABSTRACT

A baffle construction and arrangement for a flare seal drum to prevent makeup or seal water supplied to the drum from continuously flushing water saturated with undesirable dissolved materials, such as hydrogen sulfide (H2S), to the sewer while preventing hydrocarbon buildup within the flare seal drum.

United States Patent Richards et al.

[ 51 Sept. 19, 1972 [54] BAFFLE CONSTRUCTION FOR FLARE SEAL impMsInventors: John F. Richards Baton Rouge:

La. 70806; Walter L. Terrell, Jr., elflaakaifififi- Assignee: EssoResearch and Engineering r e e e Filed: June 18, 1970 Appl. No.: 47,527

US. Cl. ..55/227, 55/244, 55/256, 261/8 Int. Cl. ..B0ld 47/02 Field ofSearch ..55/255, 256, 355, 227, 244, 55/421, 73, 245-254, 355; 261/8References Cited UNITED STATES PATENTS 835,243 il /1906 Jetifreysw.15M421:

2,180,849 11/1939 Printz ..55/228 2,484,277 10/1949 Fisher ..55/2282,850,877 9/1958 Slomer ..55/256 3,387,432 6/1968 Ferrara ..55/2283,451,198 6/1969 Axelsson ..55/485 2,164,833 7/1939 Norman ..55/227Primary Examiner-Bernard Nozick Attorney-Manahan and Wohlers and F.Donald Paris [5 7] ABSTRACT A baffle construction and arrangement for aflare seal drum to prevent makeup or seal water supplied to the drumfrom continuously flushing water saturated with undesirable dissolvedmaterials, such as hydrogen sulfide (H S), to the sewer while preventinghydrocarbon buildup within the flare seal drum.

6 Claims, 1 Drawing Figure 49 ama/4s BAFFLE CONSTRUCTION FOR FLARE SEALDRUMS BACKGROUND OF THE INVENTION A conventional design for a flare sealdrum generally provides for a makeup water rate of approximately 40gallons/minute (GPM) to insure prompt reestablishment of the water sealafter a blow has occurred. When a stream being flared contains hydrogensulfide (H 8), the seal water becomes saturated and carries the hydrogensulfide (H 8) out with it into the sewer. The sewer normally is hot sothat the poisonous hydrogen sulfide (H 8) is released thereby creating adangerous situation. One possibility is that the water could be injecteddirectly into the dip leg to avoid flushing hydrogen sulfide (H 8) intothe sewer, but this arrangement would permit an undesirable buildup ofcondensed hydrocarbons in the seal drum. Other prior art seal drumconstructions utilize a single baffle, which functions as an overflowweir, wherein the makeup water is supplied directly into the mainportion of the seal drum thereby causing the hydrogen sulfide-saturatedwater to overflow and subsequently be carried out of the seal drum intothe sewer. As previously mentioned, this type of arrangement isundesirable because of the fact that poisonous hydrogen sulfide (H 8)will be released in the hot sewer to create a relatively dangeroussituation.

For background purposes, the present invention is employed in anapparatus and process for flaring combustible gaseous materials andespecially for the flaring and burning of gaseous hydrocarbon materialwhere such materials are derived from operations for the refining ofpetroleum oils in various industrial operations and more particularly,in the refining of petroleum oils, large volumes of combustible gaseousmaterials are produced. As is apparent, some of these materials have noreal economic value as fuel or otherwise, and therefore must be disposedof in a suitable manner. Further, such materials result from upsetconditions in the normal operation of a refinery wherein gases whichordinarily might be subjected to further processing in order to obtainvaluable products therefrom must be vented in order to avoid theoccurrence of dangerously abnormal pressures in operating equipment. Thetotal volume of all such accumulations of gases in normal refineryoperation and the hazardous nature thereof make it almost impossible forsuch gases to be discharged directly into the atmosphere. Thus, inpractice it is customary to burn such gases as they are discharged froman exhaust or flare stack at a considerable distance above the groundalthough on occasion for the sake of economy, burning may beaccomplished in relatively low large diameter enclosures or flarestructures. The flare seal drum fits into the overall flaring apparatusand process in that it prevents flashback, that is, it prevents abackfeed of the flame. By preventing any backfeed of air the possibilityof combustion is substantially eliminated and thus, an explosivesituation is avoided. As mentioned heretofore, the prior art hassuggested various flare seal drum constructions and arrangements forpreventing the dispersement of hydrogen sulfide-saturated water frombeing carried out into the sewer, but for the most part the prior arthas been unsuccessful in solving this problem.

SUMMARY OF THE INVENTION The present invention overcomes thedeficiencies of the prior art and is designed to prevent the makeupwater or liquid seal supply from continuously flushing water saturatedwith hydrogen sulfide (H s) to the sewer while preventing a hydrocarbonbuildup in the flare seal drum.

The flare seal drum construction and arrangement for overcoming thedeficiencies of the prior art comprises a series of baffles installed atone end, for example the overflow end of the seal drum such that bafflesprevent essentially all mixing of the makeup waterwith the hydrogensulfide-saturated water already in the seal drum and thus, any overflowwill contain very little hydrogen sulfide (H 8). At the same time thebaffles permit the water to displace any condensed hydrocarbons becauseof the difference in gravity so that the water will overflow to thesewer and no buildup will occur. Toward this end the seal drum isprovided at its overflow end with preferably three longitudinally spacedbaffles, two of which are of the same height with the second orintermediate baffle being slightly lower in height than the other twobaffles. In a flare seal drum constructed according to the teachings ofthe present invention, the inlet for the liquid seal supply or makeupwater is located at the baffle end between the two baffles closest theoverflow end to effectively segregate the water flow through the drumfrom the gases being flared. Also, there is provided a third bafflesituated furthest from the overflow end of the drum for cooperating withthe other baffles to prevent any mixing between the hydrogensulfide-saturated water and the incoming makeup water. In effect, thesebaffles confine the hydrogen sulfide-saturated water within apredetermined area or main portion of the seal drum, or in other words,the hydrogen sulfide-saturated water is confined in a backpocket of thedrum thereby preventing any overflow and subsequent drainage into thesewer. As the makeup water flows into the seal drum it is separated fromthe hydrogen sulfide-saturated water so that this new water supplycannot pick up any significant amount of the hydrogen sulfide-saturatedwater. Thus, any water overflow will be of water containing a minimum orpermissible amount ofhydrogen sulfide (H 8) that will not create anundesirable situation to occur once the water passes into the sewer.

Accordingly, it is a primary object of the present invention to providea novel and improved construction and arrangement for a flare seal drumfor preventing incoming makeup water from continuously flushing watersaturated with hydrogen sulfide (H 8) to the sewer while at the sametime preventing any undesirable hydrocarbon buildup in the flare sealdrum.

A further object of the present invention is to provide a novel andimproved construction for a flare seal drum which employs a series ofbaffles to prevent the flushing of water saturated with hydrogen sulfide(H 8) from the drum.

Having in mind the above and other objects that will be evident from anunderstanding of this disclosure, the invention comprises thecombinations and arrangements as illustrated in the presently preferredembodiment of the invention which thereinafter set forth in BRIEFDESCRIPTION OF THE DRAWING g The drawing illustrates schematically aflare seal drum constructed and arranged according to the teachings ofthe instant invention.

' DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing referencenumeral designates an elongated flare seal drum having elliptical-shapedends and a conduit inlet 11 for receiving disposable and combustiblegases from a main conduit (not shown). The conduit 11 extends into theflare seal drum l0 and terminates below the surface or water level(W.L.) of a body of 'seal liquid designated 12 which is maintainedtherein substantially-at the level of the overflow weirs or baffles 13and, which water level typically may be approximately 24 to 48. inches.As illustrated, a valved conduit line 15 provides an inlet for themakeup water or liquid seal for the drum 10. The inlet 15 is disposed toenter the drum 10 at its overflow end designated 24, between theoverflow weir-or baffle 13 and a third baffle l6 spaced intermediateequidistant from the baffles Band 14. Further, the overflow weirs 13 and14 terminate at the same height relative to the bottom of the drum 10,whereas the intermediate baffle 16 has a height slightly less, forexample, two inches below the normalwater level (W.L.) of the sealliquid 12. For drainage of the overflow seal liquid from the drum 10,there is provided a conduit 17 connected adjacent the overflow end 24 ofthe drum 10. In the event that it is desirable or necessary tocompletely drain the flare seal drum 10 of the liquid 12 containedtherein, provision is made therefore by providing a conventional valveddrainage conduit connection 18 adjacent the opposite end of the drum 10.Further, an aperture or weep hole 19 may be provided in the intermediatebaffle 16 adjacent the lower'end thereof to permit drainage ofsubstantially all the water from the drum, particularly that in thevicinity of the baffles. The conduit connections 20, 21, whichcommunicate with the upper portion of minate approximately four inchesabove the bottom of the flare seal drum and may extend to a height of 38inches which will accommodate the maximum water level in the drum. Thedimensions previously set forth I are intended to be illustrative onlyand are not intended to be limiting upon the present invention, since itis readily apparent that depending on the particular situation and factsinvolved, the dimensions may vary one way or the other and readily wouldbe within the skill of those working in the art once the teachings ofthe present invention were known to them.

As illustrated, the lower portion of the vessel atthe overflow endcontains the baffle construction and arrangement previously described.These baffles, which are made of carbon steel, may be circular in natureor of any other suitable shape that corresponds to the vention, there isa significant reduction in the amount the drum [0 above the level (W.L.)of seal liquid 12,

seam length (excluding the elliptical end) of about 30 feet. Asmentioned hereinbefore, the water level may be about 24 inches with thegas inlet conduit 11 being disposed approximately 18 inches below thewater level (W.L.)or 14 inches above the bottom of the drum 10. Atypical arrangement of the internal baffle construction may be whereinthe intermediate baffle 16 is spaced about one-half to one footequidistantly from the baffles 13 and 14. The baffle l4 typically mayterof material (e.g., l-I,S) dissolved in the water leaving the sealdrum. This is particularly beneficial in meeting the requirements forsafety and clean water that leaves the refinery. It is clear that byconstructing a flare seal drum according to the teachings of the presentinvention .as disclosed heretofore, the water that flows through thedrum is substantially'segregated from any of the gases that are, beingflared- Also, by installing the baffle arrangement as illustrated anddescribed, the amount of material dissolved in the water leaving theseal drum is greatly reduced. This reduction in the material dissolvedin the water significantly reduces taste and odor. Further, thedisclosed construction and arrangement is preferable to installingfacilities that would permit reusing the seal water in the same sealsince the purge from the reuse system would be much more highlyconcentrated in the taste and odor producing materials, and theiroverall reduction to the sewers would be less than for disclosed baffleconstruction and arrangement. Further, there is the possibility that areuse system would create corrosion problems due to the concentratingcorrosive materials. Thus, it is apparent that the present constructionand arrangement will substantially reduce taste and odor problems thatare present in the effluent, and further reduces the investment for anysecondary treatment that may have been required heretofore to eliminatecertain of the dissolved materials in the water.

Although the instant invention has been described with a certain degreeof particularity, it is to be understood that the present disclosure hasbeen made by way of an example and that obviously changes in the detailsof construction and arrangement of parts may be restored to withoutdeparting from the spirit and scope of the invention. Thus, theconstruction and arrangement of the flare seal drum described andillustrated for use with an elevated flare or vent, would be equallyapplicable where the vapors are disposed to a furnace burning pit,ground flare or the like. Accordingly, reference should be made to thefollowing appended claims in determining the full scope of the invention.

What is claimed herein is:

1. A flare seal drum containing a body of liquid seal having apredetermined upper surface level employed in a system for flaringcombustible gaseous materials, said seal drum comprising an elongatedvessel having a top and first and second ends, inlet conduit means forreceiving combustible gaseous materials and extending through said topinto said seal drum to a level substantially below said predeterminedupper surface level to form a liquid contaminated with undesirabledissolved materials, outlet conduit means operably communicating withthe upper portion of said seal drum above said predetermined uppersurface level providing for release of gaseous material from said sealdrum, a plurality of baffle means operably secured to said vessel andlongitudinally spaced apart at said first end of said vessel forpreventing any substantial mixing of the contaminated liquid with cleanliquid seal supplied to the drum and substantially confining thecontaminated liquid to a predetermined area in said drum tosubstantially reduce the amount of overflow and drainage of saidcontaminated liquid from said drum, said bafi'le means comprising firstbaffle means spaced from said first end and second baffle means spacedfrom said first baffle means on the side opposite said first end inletmeans for supplying a steady flow of liquid seal to said vessel disposedbetween said first and second baffle means, and outlet means forremoving the substantially uncontaminated overflow liquid from saidvessel and located between said first baffle means and said first end.

2. A flare seal drum according to claim 1 wherein said plurality ofbaffle means includes a third baffle longitudinally-spaced from saidsecond baffle on the side opposite said first end.

3. A flare seal drum according to claim 1 wherein said plurality ofbaffle means includes a third baffle longitudinally-spaced from saidsecond baffle on the side opposite said first end, said baffles operablysecured to said vessel and conforming in shape therewith, said firstbaffle being spaced from said one end of said vessel and extendingupwardly from the bottom of said vessel for a first predeterminedheight, said second baffle being longitudinally-spaced from said firstbaffle on the side thereof opposite said first end of said vessel andextending upwardly from the bottom of said vessel for a secondpredetermined height which is less than said first predetermined height,said third baffle being longitudinally-spaced from said second baffle onthe side opposite from said one end of said vessel and terminatsaidsecond baffle is longitudinally spaced equidistant from said first andthird baffles.

6. A flare seal drum according to claim 5 wherein said second baffleincludes an aperture at the end thereof adjacent the bottom of saidvessel.

2. A flare seal drum according to claim 1 wherein said plurality ofbaffle means includes a third baffle longitudinally-spaced from saidsecond baffle On the side opposite said first end.
 3. A flare seal drumaccording to claim 1 wherein said plurality of baffle means includes athird baffle longitudinally-spaced from said second baffle on the sideopposite said first end, said baffles operably secured to said vesseland conforming in shape therewith, said first baffle being spaced fromsaid one end of said vessel and extending upwardly from the bottom ofsaid vessel for a first predetermined height, said second baffle beinglongitudinally-spaced from said first baffle on the side thereofopposite said first end of said vessel and extending upwardly from thebottom of said vessel for a second predetermined height which is lessthan said first predetermined height, said third baffle beinglongitudinally-spaced from said second baffle on the side opposite fromsaid one end of said vessel and terminating at one end at a levelcorresponding to said first predetermined height.
 4. A flare seal drumaccording to claim 3 wherein the other end of said third baffle isspaced a predetermined amount above the bottom of said vessel.
 5. Aflare seal drum according to claim 4 wherein said second baffle islongitudinally spaced equidistant from said first and third baffles. 6.A flare seal drum according to claim 5 wherein said second baffleincludes an aperture at the end thereof adjacent the bottom of saidvessel.